python: SSA for names in except*

Author: yoff

python/ql/lib/semmle/python/essa/Definitions.qll

@@ -69,6 +69,8 @@ abstract class SsaSourceVariable extends @py_variable {
     or
     SsaSource::exception_capture(this, def)
     or
+    SsaSource::exception_group_capture(this, def)
+    or
     SsaSource::with_definition(this, def)
     or
     SsaSource::pattern_capture_definition(this, def)

python/ql/lib/semmle/python/essa/Essa.qll

@@ -511,14 +511,14 @@ class AssignmentDefinition extends EssaNodeDefinition {
   override string getAPrimaryQlClass() { result = "AssignmentDefinition" }
 }
 
-/** A capture of a raised exception `except ExceptionType ex:` */
+/** A capture of a raised exception `except ExceptionType as ex:` */
 class ExceptionCapture extends EssaNodeDefinition {
   ExceptionCapture() {
     SsaSource::exception_capture(this.getSourceVariable(), this.getDefiningNode())
   }
 
   ControlFlowNode getType() {
-    exists(ExceptFlowNode ex |
+    exists(ExceptGroupFlowNode ex |
       ex.getName() = this.getDefiningNode() and
       result = ex.getType()
     )
@@ -529,6 +529,24 @@ class ExceptionCapture extends EssaNodeDefinition {
   override string getAPrimaryQlClass() { result = "ExceptionCapture" }
 }
 
+/** A capture of a raised exception group `except* ExceptionType as ex:` */
+class ExceptionGroupCapture extends EssaNodeDefinition {
+  ExceptionGroupCapture() {
+    SsaSource::exception_group_capture(this.getSourceVariable(), this.getDefiningNode())
+  }
+
+  ControlFlowNode getType() {
+    exists(ExceptGroupFlowNode ex |
+      ex.getName() = this.getDefiningNode() and
+      result = ex.getType()
+    )
+  }
+
+  override string getRepresentation() { result = "except* " + this.getSourceVariable().getName() }
+
+  override string getAPrimaryQlClass() { result = "ExceptionGroupCapture" }
+}
+
 /** An assignment to a variable as part of a multiple assignment `..., v, ... = val` */
 class MultiAssignmentDefinition extends EssaNodeDefinition {
   MultiAssignmentDefinition() {

python/ql/lib/semmle/python/essa/SsaDefinitions.qll

@@ -30,6 +30,13 @@ module SsaSource {
     exists(ExceptFlowNode ex | ex.getName() = defn)
   }
 
+  /** Holds if `v` is defined by assignment of the captured exception group. */
+  cached
+  predicate exception_group_capture(Variable v, NameNode defn) {
+    defn.defines(v) and
+    exists(ExceptGroupFlowNode ex | ex.getName() = defn)
+  }
+
   /** Holds if `v` is defined by a with statement. */
   cached
   predicate with_definition(Variable v, ControlFlowNode defn) {